• 대한화장품학회지
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• 제42권2호
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• pp.127-133
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• 2016

본 연구에서는 정제수/Span 80-Nikkol BL 25/오일계의 water-in-oil (W/O) 나노에멀젼을 높은 온도에서 PIC 유화로 제조하였다. 이 방법은 본 시스템에서 미세하게 분산된 저점도의 W/O 나노에멀젼의 형성을 가능케 하였다. 그러나 실온에서 PIC 방법으로 제조된 에멀젼은 나노에멀젼보다는 마크로에멀젼이 제조되었다. 유화온도가 $30^{\circ}C$에서 $80^{\circ}C$로 증가하면 온도에 따른 계면장력의 큰 변화의 결과로 입자 크기는 $2{\mu}m$에서 100 nm 정도로 감소하였다. $80^{\circ}C$에서 제조된 나노에멀젼의 입자 크기는 50 ~ 200 nm 범위에 있었고 내상의 분율은 15 wt%까지 가능하였다. 또한 혼합 유화제의 최적 HLB는 7.0 부근에서 가장 안정한 나노에멀젼이 형성되었다. 제조된 나노에멀젼은 1개월 이상 실온에서 안정하였다. 본 연구 결과는 저점도의 W/O 나노에멀젼의 형성 최적화에 중요한 정보를 제공할 수 있다. 이 결과는 W/O 나노에멀젼의 저점도로 인한 부드러운 사용감 등으로 화장품 제형으로 유용하게 이용될 것으로 생각된다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 가을 학술발표회 논문집
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• pp.853-858
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• 2001

The PSC bridge being built by ILM may have greater bending moment during its construction rather than after completion. When it occurs, Engineer should suggest to reduce stress-resultants than to make bigger cross-section with considering stability ,economics, and proper span-to-depth ratio. The used method is to install extruded nose at the end of girder. It substitutes the weighted segment for the light. From the reference, the stiffness of extruded nose, is 1/10 of the main girder, and the length is 60 to 70% of the length of the span, with little justification. In this study, the proper length and stiffness of the nose element is determined by the parametric study and idealizing procedure. The results about the extruded nose through the mixing of the parameter of its stiffness and length, the proper length of extruded nose is 80% of the longest span and the proper stiffenss is 13% of the bending stiffness of the superstructure and the proper length of extruded nose is 70% of the longest span and the proper stiffness is 9.5% of the bending stiffness of the superstructure.

• 한국안전학회지
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• 제31권1호
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• pp.74-80
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• 2016

In this paper, structural characteristics for an extradosed prestressed concrete box girder bridge are investigated in terms of selective parameters. These parameters are mainly associated with the structural details of the extradosed bridge and derived from currently available literatures regarding previous design drawings. The analyses have been carried out using general-purpose structural analysis program, RM-Space Frame. The parameters evaluated for the present study represent the most salient features of the extradosed bridge and are as follows; 1) span length ratio(side-span length to center-span length), 2) boundary condition of girder, 3) height of pylon, 4) anchorage location of external cables and 5) girder stiffness. The analytical predictions indicate that span length ratio and pylon height are reasonably adequate in the range of 0.55 to 0.60 and $L_m/8$ to $L_m/12$ respectively for the bridge under consideration. Also, demonstrated is the boundary condition of girder, in which rigid-connection details give more efficiency than the continuous details. In addition, considering structural characteristics of the extradosed bridge, it is desirable that the girder stiffness should be determined by the stress range of external cables rather than bending moment of girder.

• 한국의류학회지
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• 제24권7호
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• pp.1065-1072
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• 2000

The molecular areas and the interfacial tension behavior of ten nonionic surfactants, i.e., Span 20 and Tween 20, 40, 60. 80, 21, 61, 81, 65, & 85 are tested to assay their effects on the wetting and liquid retention properties of hydrophilic and hydrophobic fibrous materials. The molecular areas at water/air interface are derived from Gibbs’adsorption equations. The following conclusions are drawn from the results: 1) Span 20 is efficient in lowering the interfacial tension and effective in adsorption at the water/air interface, resulting in the low interfacial tension at critical micelle concentration (${\gamma}$$_{CMC}$) and a small molecular area($\omega$), 2) when the hydrophiles of the surfactants are constant, $\omega$’s increase as hydrophobe carbon numbers of the surfactants increase, 3) when the hydrophobes are constant, ${\gamma}$$_{CMC}$’s and $\omega$’s increase as the hydrophile ethylene oxide units increase, indicating effectiveness and efficiency is parallel in this case, 4) the ethylene oxide unit length as a hydrophile has greater influence on u than the hydrophobe chain length.han the hydrophobe chain length.gth.

• Structural Engineering and Mechanics
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• 제56권5호
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• pp.813-833
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• 2015

Spherical reticulated shells are widely applied in structural engineering due to their good bearing capability and attractive appearance. Parametric modeling of spherical reticulated shells is the basis of internal analysis and optimization design. In the present study, generation methods of nodes and the corresponding connection methods of rod elements are proposed. Modeling programs are compiled by adopting the ANSYS Parametric Design Language (APDL). A shape optimization method based on the two-stage algorithm is presented, and the corresponding optimization program is compiled in FORTRAN environment. Shape optimization is carried out based on the objective function of the minimum total steel consumption and the restriction condition of strength, stiffness, slenderness ratio, stability. The shape optimization of four typical Schwedler spherical reticulated shells is calculated with the span of 30 m~80 m and rise to span ratio of 1/7~1/2. Compared with the shape optimization results, the variation rules of total steel consumption along with the span and rise to span ratio are discussed. The results show that: (1) The left and right rod-Schwedler spherical reticulated shell is the most optimized and should be preferentially adopted in structural engineering. (2) The left diagonal rod-Schwedler spherical reticulated shell is second only to left and right rod regarding the mechanical behavior and optimized results. It can be applied to medium and small-span structures. (3) Double slash rod-Schwedler spherical reticulated shell is advantageous in mechanical behavior but with the largest total weight. Thus, this type can be used in large-span structures as far as possible. (4) The mechanical performance of no latitudinal rod-Schwedler spherical reticulated shell is the worst and with the second largest weight. Thus, this spherical reticulated shell should not be adopted generally in engineering.

• 대한화장품학회지
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• 제43권4호
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• pp.273-279
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• 2017

본 실험에서는 화장품에 널리 사용되는 지방산과 지방알코올을 Tween 80과 Span 80을 함께 사용하여 조성 상전이 유화법으로 O/W (oil-in-water) 저점도 나노에멀젼을 제조하였다. 지방알코올의 오일상에서의 농도가 증가할수록 나노에멀젼의 입자 크기가 증가하였다. 혼합계면활성제의 HLB를 조절하여 입도 분포가 좁고 안정한 나노에멀젼의 제조가 가능하였다. 전상점 부근에서 지방산 및 지방알코올을 함유한 계 모두에서 유사한 점도와 전기전도도의 변화를 보였으나 오일과 계면활성제만으로 구성된 계와는 다르게 넓은 수용액상 분율범위에서 높은 점도를 나타냈다. 입자 크기가 100 nm 미만의 저점도 나노에멀젼은 실온에서 한 달 이상 안정하였다. 지방산 또는 지방알코올을 함유하고, 저에너지 유화법으로 제조된 저점도 O/W 나노에멀젼 제형은 화장품의 기재로서 널리 사용될 수 있다.

• Steel and Composite Structures
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• 제21권1호
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• pp.217-247
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• 2016

Five extended cylindrical reticulated shells are proposed by changing distribution rule of diagonal rods based on three fundamental types. Modeling programs for fundamental types and extended types of cylindrical reticulated shell are compiled by using the ANSYS Parametric Design Language (APDL). On this basis, conditional formulas are derived when the grid shape of cylindrical reticulated shells is equilateral triangle. Internal force analysis of cylindrical reticulated shells is carried out. The variation and distribution regularities of maximum displacement and stress are studied. A shape optimization program is proposed by adopting the sequence two-stage algorithm (RDQA) in FORTRAN environment based on the characteristics of cylindrical reticulated shells and the ideas of discrete variable optimization design. Shape optimization is achieved by considering the objective function of the minimum total steel consumption, global and locality constraints. The shape optimization for three fundamental types and five extended types is calculated with the span of 30 m~80 m and rise-span ratio of 1/7~1/3. The variations of the total steel consumption along with the span and rise-span ratio are analyzed with contrast to the results of shape optimization. The optimal combination of main design parameters for five extended cylindrical reticulated shells is investigated. The total steel consumption affected by distribution rule of diagonal rods is discussed. The results show that: (1) Parametric modeling method is simple, efficient and practical, which can quickly generate different types of cylindrical reticulated shells. (2) The mechanical properties of five extended cylindrical reticulated shells are better than their fundamental types. (3) The total steel consumption of cylindrical reticulated shells is optimized to be the least when rise-span ratio is 1/6. (4) The extended type of three-way grid cylindrical reticulated shell should be preferentially adopted in practical engineering. (5) The grid shape of reticulated shells should be designed to equilateral triangle as much as possible because of its reasonable stress and the lowest total steel consumption.

• 한국전문물리치료학회지
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• 제21권3호
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• pp.80-88
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• 2014

Previous studies have reported that decreased cognitive ability has been consistently associated with significant declines in performance of one or both tasks under a dual-task walking condition. This study examined the relationship between specific cognitive abilities and the dual-task costs (DTCs) of spatio-temporal gait parameters in stroke patients. The spatio-temporal gait parameters were measured among 30 stroke patients while walking with and without a cognitive task (Stroop Word-Color Task) at the study participant's preferred walking speed. Cognitive abilities were measured using Computerized Neuropsychological Testing. Pearson's correlation coefficients (r) were calculated to quantify the associations between the neuropsychological measures and the DTCs in the spatio-temporal gait parameters. Moderate to strong correlations were found between the Auditory Continuous Performance test (ACPT) and the DTCs of the Single Support Time of Non-paretic (r=.37), the Trail Making A (TMA) test and the DTCs of Velocity (r=.71), TMA test and the DTCs of the Step Length of Paretic (r=.37), TMA test and the DTCs of the Step Length Non-paretic (r=.36), the Trail Making B (TMB) test and the DTCs of Velocity (r=.70), the Stroop Word-Color test and the DTCs of Velocity (r=-.40), Visual-span Backward (V-span B) test and the DTCs of Velocity (r=-.41), V-span B test and the DTCs of the Double Support Time of Non-paretic (r=.38), Digit-span Forward test and the DTCs of the Step Time of Non-paretic (r=-.39), and Digit-span Backward test and the DTCs of the Single Support Time of Paretic (r=.36). Especially TMA test and TMB test were found to be more strongly correlated to the DTCs of gait velocity than the other correlations. Understanding these cognitive features will provide guidance for identifying dual- task walking ability.

• 한국세라믹학회지
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• 제51권5호
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• pp.477-480
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• 2014

An $Al_2O_3$-CuO-ZnO (ACZ) precursor powder was synthesized by a facial sol-gel process using a nonionic surfactant span 80 as the chelating agent to improve the surface area and morphology. When creating a hydrogen membrane, several kinds of properties are required, such as easy dissociation of hydrogen molecules, fast hydrogen diffusion, high hydrogen solubility, and resistance to hydrogen embrittlement. ACZ-Ni composite membranes (cermet) were prepared with this precursor and pure Ni powder via the hot press sintering (HPS) method. The ACZ powder was characterized by XRD, BET, and FE-SEM. Hydrogen permeation experiments were performed by Sievert's type of hydrogen permeation membrane equipment. The hydrogen permeability of ACZ/Ni 10 wt% and ACZ/Ni 20 wt% was obtained as 7.2 and $10molm^{-2}s^{-1}$ at RT, respectively. These values of the corresponding membranes were slightly increased with increasing pressures.

• 공업화학
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• 제9권6호
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• pp.846-851
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• 1998

w/o 에멀젼 내에서 균일용액침전반응을 진행시켜 산화아연 미세 입자를 제조하는 실험적 연구를 수행하였다. 질산아연 수용액에 hexamethylene tetramine (HMTA)을 침전제로 첨가한 침전액은 유화제 Span 80에 의해 kerosine과 안정한 w/o 에멀젼을 형성하였다. 얻어진 w/o 에멀젼을 HMTA 분해온도 이상($85^{\circ}C$)으로 가열하여 w/o 에멀젼 내에서 균일용액 침전반응을 진행시키면 산화아연 입자들이 제조되는 것을 확인하였다. 이렇게 제조된 산화아연 입자들은 이중분산 (bi-modal distribution)을 갖는 영역이 존재하기도 하였으나, 균일용액침전법에 비하여 높은 초기 아연농도와 높은 수율에서도 입자가 작고 입도분포가 비교적 좁은 산화아연 입자들을 얻을 수 있었다.